to feel confused by the level of affection one feels for nicknames on a screen?

I'm a bit late to the party, having only just discovered MN (never been on other "chat" type sites either). It really feels like people care about each other here, and (like countless others, it seems) I continually find myself "checking" on people on certain threads, and thinking about some posters' welfare very regularly.

I can't formulate my question exactly, but isn't it a bit weird that none of us really knows each other? Or do we? What does it all mean?! People who have been on MN a long time: do you feel that you have real "friendships" here?